408 THE EXTERNAL CONFIGURATION 



upon the customary size attained by such animals* 

 those that are small may have none, whilst allied animals 

 of larger size may have more or less developed convolu- 

 tions. Yet it certainly cannot he said that larger animals 

 are necessarily more intelligent than smaller animals. 



As to the reason of the greater convolutional develop- 

 ment met with in larger animals Carl Yogt says t : 



" Happily, mathematics will assist us here. On comparing two 

 bodies of similar form but of different size, their respective 

 volumes vary as the cube of their diameters, whilst the proportion 

 of the surfaces is as the square of the diameters, or, in other words, 

 the volume of a body increases more rapidly than the surface, and 

 this more rapidly than the diameter. Every artillerist knows well 

 that a twelve-pounder, though thrice as heavy as a four-pounder, 

 does not nearly possess a diameter thrice as large ... In applying 

 this principle to the head, and especially the cranium of animals, 

 it will be seen -that in every natural group or order of mammals, 

 the head, and especially the cranial capacity, stands in a certain 

 relation to the body, which is nearly constant in the various species 

 . . .that the surface of the internal cranial capacity is proportion- 

 ately smaller in the larger animal, and that consequently, in order 

 to secure a similar surface of grey matter, it must be convoluted 

 in the large animal, whilst it may remain smooth in the small 

 animal." 



If we look then from a broad, general point of view at 

 the problem as to the degree of importance to be attached 

 to the great convolutional complexity of the brain of 

 Man, it is apt to appear, at first sight, that this particular 

 feature may be a necessary appanage or sequence of the 

 size of Man's body, ^s compared with that of Monkeys 

 and of Apes. Man, in respect of convolutional develop- 

 ment, appears to stand far away at the head of the 

 Quadrumanous type, just as the Elephant stands at the 

 head of the Herbivorous type, and just as the great Whales 



* See p. 276. 



f " Lectures on Man " (Anthrop. Soc. Transln.), p. 105. 



